Life and health

Carbuncle

Carbuncle: a deep staphylococcal skin infection of adjacent hair follicles forming a cluster of interconnected boils (furuncles), typically on the neck or back, treated by incision and drainage.

Carcharhiniformes (ground sharks), the largest shark order: 8 families, 51 genera, 337+ species including requiem sharks, hammerheads, tiger shark, and catsharks; diagnosed by nictitating lower eyelids, two spineless dorsal fins, and an anal fin.

Carcharhinus falciformis

Carcharhinus falciformis, the silky shark (Bibron, 1839), a circumtropical pelagic requiem shark up to 3.5 m, IUCN Vulnerable, CITES Appendix II since 2017, heavily fished for fins and tuna-fishery bycatch.

Carcharhinus perezii

Carcharhinus perezii, the Caribbean reef shark (also spelled C. perezi), a large requiem shark of western Atlantic coral reefs from North Carolina to Brazil; IUCN Endangered (2021), biennial reproduction, 3-6 pups, CITES Appendix II.

Carcharhinus plumbeus

Carcharhinus plumbeus, the sandbar shark, also called thickskin or brown shark, is a requiem shark up to 8 feet long found in coastal waters worldwide.

Carcharodon hastalis

Carcharodon hastalis, also called Isurus or Cosmopolitodus hastalis, is an extinct lamnid shark of the Miocene and Pliocene (about 20 to 3 million years ago) with smooth, unserrated teeth 2.5 to 7.5 cm tall, regarded by many as the ancestor of the great white shark.

Carcharodontosaurus

Carcharodontosaurus, shark-toothed lizard, giant carcharodontosaurid theropod from Late Cretaceous North Africa (99–94 Ma), about 12.5 m long; Egyptian fossils destroyed in 1944, Egyptian specimen renamed Tameryraptor in 2025.

Carcinisation

Carcinisation, also spelled carcinization, is convergent evolution in which crustaceans independently evolve a crab-like body plan, named in 1916 and seen at least five times.

Carcinoembryonic antigen

Carcinoembryonic antigen (CEA), a glycoprotein tumor marker discovered by Gold and Freedman in 1965 at McGill, is used mainly to monitor colorectal cancer treatment and recurrence, not for screening.

Carcinogen

Carcinogen: any agent (chemical, radiation, virus, or exposure) that can cause cancer. Classified by IARC Groups 1–3 (135 Group 1 agents), NTP, and EPA; hazard classification differs from risk level.

Carcinogenesis

Carcinogenesis: the multistage process by which normal cells become malignant through accumulated genetic and epigenetic changes. Covers initiation-promotion-progression, driver mutation counts, mutational signatures, DNA repair defects, and carcinogens.

Carcinoid

Carcinoid, coined by Oberndorfer in 1907, is the older name for a well-differentiated neuroendocrine tumor of the GI tract or lung; WHO 2000 replaced it with NET/NEC; carcinoid syndrome occurs with liver metastases.

Carcinoid syndrome

Carcinoid syndrome is a group of symptoms caused when gastrointestinal carcinoid tumors release serotonin and other substances, typically after the tumor has spread to the liver.

Carcinoma

Carcinoma: cancer arising from epithelial cells lining skin and internal organs; the most common cancer type (80-90% of cases). Subtypes include adenocarcinoma, squamous, basal cell, and transitional cell carcinoma; distinct from sarcoma, leukemia, lymphoma, myeloma.

Carcinoma in situ

Carcinoma in situ, also known as in situ neoplasm, is a stage 0 condition in which cells that look like cancer remain confined to the tissue where they formed.

Carcinoma in situ of bladder

Bladder carcinoma in situ (CIS, stage 0is/Tis): flat, always high-grade, noninvasive urothelial cancer of the bladder lining; primary, concomitant, or secondary; ~54% progress untreated; treated with BCG or cystectomy.

Carcinoma in situ of breast

Carcinoma in situ of the breast (DCIS, LCIS; stage 0 breast cancer, intraductal carcinoma): noninvasive lesions confined to breast ducts or lobules; 15–25% of diagnoses, over 98% five-year survival, central overdiagnosis and active surveillance debate.

Carcinoma in situ of colon

Carcinoma in situ of the colon, also called intramucosal carcinoma or stage 0 (Tis N0 M0) colorectal cancer, is abnormal cancer-appearing cells confined to the colonic mucosa, with no metastatic risk and definitive treatment by endoscopic resection.

Carcinoma in situ of endometrium

Carcinoma in situ of endometrium (ICD-11 2E67.0, ICD-10-CM D07.0): abnormal cancer-like cells confined to the uterine lining without invasion; covers the legacy term for endometrial precancer (AH/EIN) and serous endometrial intraepithelial carcinoma.

Carcinoma in situ of larynx

Carcinoma in situ of the larynx (ICD-10 D02.0, stage 0 laryngeal cancer) is non-invasive malignant-appearing epithelium of the voice box, grouped with severe dysplasia, treated by laser endoscopic excision or radiotherapy with surveillance.

Carcinoma in situ of penis

Carcinoma in situ of the penis, also called penile intraepithelial neoplasia grade III, erythroplasia of Queyrat (glans), or Bowen's disease (shaft), is a noninvasive full-thickness squamous atypia, HPV-related, with up to 30% untreated progression risk.

Carcinoma in situ of rectum

Carcinoma in situ of the rectum is stage 0 rectal cancer in which abnormal cells remain in the rectum's innermost lining, with almost no risk of spread.

Carcinoma in situ of skin

Carcinoma in situ of skin, also called Bowen disease or intraepidermal squamous cell carcinoma (ICD-11 2E64), is full-thickness epidermal dysplasia without dermal invasion, mainly UV-, HPV-, and immunosuppression-driven, with 3–5% progression risk to invasive SCC and surgical excision as the most effective treatment.

Carcinoma in situ of stomach

Carcinoma in situ of stomach, also called stage 0 gastric cancer or Tis, is non-invasive high-grade dysplasia of the gastric mucosa (ICD-11 2E60.2), managed by endoscopic resection and discouraged as a term by WHO.

Carcinoma in situ of the conjunctiva

Carcinoma in situ of the conjunctiva (conjunctival squamous cell carcinoma in situ, CIN III/CIS, ICD-11 2E6A.0) is a preinvasive, full-thickness conjunctival epithelial dysplasia with intact basement membrane, treated by excision with cryotherapy or topical chemotherapy.

Carcinoma in situ of the cornea

Carcinoma in situ of the cornea (ICD-11 2E6A.1) is a preinvasive ocular surface squamous neoplasia stage: full-thickness corneal epithelial atypia with intact basement membrane, caused mainly by UV-B, treated by excision or topical chemotherapy.

Carcinoma in situ of trachea

Carcinoma in situ of trachea (ICD-10-CM D02.1) is preinvasive squamous cancer confined to the tracheal lining, detected mainly by advanced bronchoscopy, treatable bronchoscopically, and sometimes regressing.

Carcinoma in situ of vagina

Carcinoma in situ of vagina, also called VaIN 3 or vaginal HSIL, is a full-thickness noninvasive HPV-associated precancerous vaginal lesion, rare (0.2–2 per 100,000 women yearly), treated by laser, excision, brachytherapy, or topical agents.

Carcinoma of the ampulla of Vater

Carcinoma of the ampulla of Vater (ampullary cancer, ampullary carcinoma): rare cancer at the bile-pancreatic duct junction in the duodenum; presents with painless jaundice; treated mainly by Whipple procedure; intestinal subtype fares better than pancreatobiliary.